Coolant disappearing?

[Billymanjoe]

I got a 1991 LS400 and it was running fine until sometime last week. I drove about 10 minutes at around 50 mph and when I parked, the car started smoking under the hood a little bit. I checked under the hood and the coolant tank was pretty low so I waited about 3 hours and when I came back, I topped off the coolant tank and drove home with no issue. 

 

The check engine light was on but I made the mistake of paying it no mind. 

 

Until today, it ran fine and took me to and from work and school several times. I took my mom out to do an errand that was 5 minutes away. When we get there, the car starts smoking again but it's not much. It's putting out white smoke and it goes away pretty quick. I drive home and it starts smoking again so I get concerned. When I come home I let it cool for another 3 hours before checking the coolant tank again and it's almost empty. I top it off again and I go to pick up my little brother from school. Before we even make it back home, the front of the car starts whistling and the car starts overheating.

 

When I pull into the car port, white smoke starts pluming out the front left fender. When I pop open the hood, I notice the smoke isn't coming out from the engine but underneath the coolant tank. 

 

I don't think it's a coolant leak because when I park, there aren't any puddles or anything on the ground when I leave. What could it be?

 

Attached are pictures of where the smoke was generally coming from

[paulo57509]

Go to Autozone or any other DIY parts place and rent a cooling system tester.

 

[RX400h]

Also check your oil (on the dipstick) to see if it is milky. You may have a blown head gasket. An auto shop can check to see if there are combustion gasses in the coolant if the oil looks okay.

[JohnBros]

Wow. You need to see where the hole is. I have never worked on an LS400 but I have a 98 Gs300 and 2008 LS460. The area you are pointing to seems to be where the tube comes from the radiator for over flow. When the car leaks water from anywhere it allows the remaining water to become even hotter creating steam that normally comes from that area. Suggesting your leak could be anywhere.

1) Look around the radiator for hose leaks, 2) then the water pump for a leak. These are the general culprits.
 

You can do this by filling up the reservoir and radiator while the car is cool only. Then starting it and seeing if the steam is coming from the overflow or a leak.

If it is coming from the overflow this is a sign your leak is elsewhere.

Using a flashlight, see if you see water coming out of where the water pump is. If not then look at the hoses for water leaking if none it can be your heater hose.  Check heater hoses.  

If not these then see if oil on dipstick is milky or if water is coming out of the block anywhere. Hope it is a hose. These are easy to fix and cheaper than the other alternatives. Good luck